US3246730A

US3246730A - Mining apparatus comprising automatically advancing jacks

Info

Publication number: US3246730A
Application number: US373636A
Authority: US
Inventors: Bolton Douglas Herbert Hewlett; Potts Michael Charles; Pawling Frank
Original assignee: Dowty Mining Equipment Ltd
Current assignee: Dowty Mining Equipment Ltd
Priority date: 1964-06-09
Filing date: 1964-06-09
Publication date: 1966-04-19
Anticipated expiration: 1983-04-19

Description

April 1966 D. H. H. BOLTON ETAL 3,246,730

MINING APPARATUS COMPRISING AUTOMATICALLY ADVANCING JACKS Filed June 9, 1964 14 8 2 26 2 73 I V {I}! 7 7 7 7 5 5 5 5 5 Q 77 O O O O 6 25 9 FIG.

Imvanrroes Dwam H. H. mull/an. a PoT'fs By FRA C 'Pfl-W-LlNG ATTORNEY United States Patent 3,246,730 MINING APPARATUS COMPRISING AUTOMATI- CALLY ADVANCING JACKS Douglas Herbert Hewlett Bolton, Winchcombe, Michael Charles Potts, Prestbury, and Frank Pawling, Charlton Kings, England, assignors to Dowty Mining Equipment Limited, a British company Filed June 9, 1964, Ser. No. 373,636 8 Claims. (Cl. 198-126) This inventionrelates to minining apparatus which includes a guide means, for example a conveyor, extending along the working face of a mine for guiding a cutting machine along the working face, and a series of fluidpressure-operated jacks each operable to apply an advancing force to the guide means.

The present invention provides mining apparatus including a guide means extending along the working face of a mine for guiding a cutting machine along the working face, a series of fluid-pressure-operated jacks each operable to apply an advancing force to the guide means, and means responsive to the advance of a portion of the guide means to stop the advance of that portion of the guide means, after a predetermined advance thereof, by rendering the appropriate jack or jacks inoperative, the advance-responsive means being adjustable to vary the amount of the predetermined advance.

The amount of advance of the said portion of the guide means may be indicated by a measure of the extension of a jack associated with that portion of the guide means;

The advance-responsive means may compare a signal indicative of the amount of advance of the said portion of the guide means with a signal of a similar nature indicative of the predetermined required advance in such a manner that, when the advance of the guide means has reached the predetermined amount, the appropriate jack or jacks are rendered inoperative. The signals may be fluid-pressure signals or may be electric signals.

The saidportion of the guide means may be an end portion of the guide'means located beyond the end of the working face. of the, mine. The guide means may be a conveyorwhose. end portion carries a conveyor drive assembly. Theadvance-responsive means may be adjustedby a signal of the advance of a portion of the guide means opposite the working face in such a manner that the end portion of the guide means is advanced by substantially the same amount as the portion of the guide means opposite the working face.

Theadvance-responsive means may be manually adjustable to vary the amount of predetermined advance of the portion of the guide means.

One embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings of which, 1

FIGURE 1 is a diagrammatic view of mining apparatus incorporating the invention, and

FIGURE 2 is a diagrammatic view of part of the mining apparatus shown in FIGURE 1.

With reference to the accompanying drawings, known mining apparatus includes a conveyor 1 extending along the working face 2 of a coal mine. A cutting machine 3 guided by the conveyor'l is located between the conveyor 1 and the working face 2 and is moving along the face from left to right in the drawing. A royv of roof supports 4, of known construction extends along the working face 2 on the opposite side of the conveyor 1 to the working face 2. Each roof support 4 includes a floor-engaging member 5 carrying three hydraulic props 6. and the props 6 carry a roof-engageable member not shown in the drawing. Each roof support 4 is connected to the conveyor 1 by a double-acting hydraulic "ice jack 7 which is operable to advance the roof support 4 towards the conveyor 1 when the conveyor is fixedly anchored, and is also operable to advance the conveyor 1 relative to the roof support 4 when the latter is fixed in position. In practice, not all the jacks 7 may be doubleacting, some may be single-acting and only operable to advance the respective roof supports towards the conveyor 1. For example, only every fourth jack 7 may be double-acting.

Every double-acting jack 7 is caused to apply an advancing force to the conveyor 1 continually with its roof support 4 acting as an anchorage, except when the roof support 4 associated with the jack 7 is being advanced, for example in the manner described in US. patent application Serial No. 282,760, filed May 23, 1963, so that the conveyor 1 and cutting machine 3 are continually urged against the working face 2.

An end portion 8 of the conveyor 1 is located in a road-way 9 which extends in a direction perpendicular to the length of the working face 2. A conveyor pusher 11 includes a releasable anchorage such as a hydraulic prop 12 carried by a base 13. The prop 12 carries a roof-engaging cap not shown in the drawing. The conveyor pusher 11 also includes a double-acting hydraulic jack 14 connected to the conveyor end portion 8. The conveyor end portion 8 carries a conveyor drive assembly not shown in detail herein, and may also carry a drive assembly for the cutting machine 3.

A control assembly 15 for controlling the operation of the cutting machine 3, the conveyor 1 and the roof supports 4 is located at a position remote from the working face 2, for example in the road-way 9. This invention is only concerned with the advance of the conveyor 1, and not with operation of the cutting machine nor the roof supports. A source of hydraulic pressure 16 located in the control assembly 15 is connected to the conveyor pusher 11 by a hose 17.

As is shown more clearly in FIGURE 2, the hose 17 is connected to an electro-hydraulic valve 18 in the conveyor pusher 11. The valve 18 is normally closed and is connected by a hose 19 to the jack 14 in such a manner that, when the valve 18 is open, the supply of hydraulic fluid under pressure through the hose 19 to the jack 14 causes the jack 14 to extend and thereby to effect advance of the end portion 8. The valve 13 can be opened to cause pressurisation of hose 19 from hose 17 by the supply of an electrical current of suflicient strength to its solenoid 21, along an electric line 22 from the control assembly 15.

An electrical potentiometer 23 responsive to extension of the jack 14 has its pick-off contact 24 connected to the control assembly 15 by an electrical line 25. The control assembly 15 supplies electrical power for the potentiometer 23 by wires not shown and the pick-off contact 24 is so arranged that the line 25 conveys to the control assembly 15 an electrical signal indicative of the extended length of the jack 14.

Another electrical potentiometer 26 is responsive to the extension of the jack 7 associated with the first roof support 4, and this potentiometer '26 is connected to the control assembly 15 by an electric line 27 which conveys to the control assembly 15 an electric signal indicative of the length of the jack 7.

In the control assembly 15,

lines

25 and 27 are connected to an electric comparator 2% whose function is to compare the electric signals in

lines

25 and 27. Line 29 is connected to an amplifier 31 which amplifies the output of the comparator 28 and sends the amplified output along line 22 to the solenoid 21 of electro-hydraulic valve 18. Besides comparing the electric signals in line 25 and in line 27, the comparator 28 can also compare the electric signals in line 25 and in line 32 which is connected to a manually-adjustable electric signal source 33.

Thus, in operation of the apparatus, with the prop 12 of the conveyor pusher 11 and the props 6 of the roof support 4 all set against the roof, the double-acting jacks 7 continually urge the conveyor 1 and the cutting machine 3 against the working face 2 as the cutting machine 3 travels to and fro along the working face in a coal-cutting manner. As coal is cut from the working face and the cutting machine leaves the vicinity of each double-acting jack 7, the jack 7 will move the conveyor 1 forwardly.

The potentiometer 26 responsive to the extension of the jack 7 on the first roof support 4 continually sends to the comparator 28 a signal indicative of the extension of this jack 7, that is to say a signal indicative of the amount of advance of the portion of the conveyor 1 in front of the first roof support 4. Also, the potentiometer 23 responsive to the extension of the jack 14 of the conveyor pusher 11 continually sends to the comparator 28 a signal indicative of the extension of the jack 14, that is to say a signal indicative of the distance between the conveyor end portion 8 and the prop 12 of the conveyor pusher 11.

While the difference between the two signals is small, the amplified output from the comparator 28 is not sufficient to operate the electro-hydraulic valve 18, but when the portion of the conveyor 1 in front of the first roof support 4 has advanced a predetermined amount relative to the conveyor end portion 8,,the diflerence between the signals in

lines

25 and 27 will be sufiicient to cause the amplified output in line 22 to actuate the electro-hydraulic valve 18 with resultant actuation of the jack 14 and advance of the conveyor end portion 8 with the prop 12 acting as an anchorage. As the conveyor end portion 8 advances, the signal from the potentiometer 23 approaches the value of the signal from the potentiometer 26 and, when the difference between the two signals falls to a predetermined amount, the amplified output of the difference becomes too small to maintain the actuation of the electrohydraulic valve 18 which therefore closes, and the jack 14 ceases advancing the conveyor end portion 8. It may be arranged that the value of the signal in line 22 required to actuate the electro-hydraulic valve 18 is a predetermined amount greater than that required to maintain the valve 18 in the actuated position so as to reduce the likelihood of the valve 18 "being continually actuated and de-actuated.

Thus, the conveyor end portion 8 advances in a manner consistent with the advance of the portion of the conveyor 1 opposite the working face 2. From time to time, it is necessary to advance the prop 12 by releasing it from the roof and contracting the jack 14, and to advance the roof supports 4 by releasing the props 6 of each roof support 4 from the roof and contracting the relevant jack 7. The roof supports 4 may be advanced in a predetermined sequence by known means while the cutting machine 3 is still operating or the cutting machine 3 may be operated until all the jacks 7 are fully extended whereupon the cutting machine 3 is stopped and the roof supports 4 are then advanced in a predetermined sequence.

To cater for inaccuracies which may occur, the full extension of the jack 7 of the first roof support 4 maybe arranged to cause the full extension of the jack 14.

If it is desired to advance the conveyor end portion 8 by some manually-selected predetermined amount, the comparator 28 is caused to compare the signals in

lines

25 and 32 instead of the signals in

lines

25 and 27. The signal in line 32 is adjusted by manual adjustment of the electric signal source 33 to produce a signal in line 32 indicative of the required advance of the conveyor end portion 3.

If due to the characteristics of the cutting machine 3, the conveyor 1 does not require to be continually urged against the face, but requires to be advanced by adjustable amounts, each double-acting jack 7 may be controlled in a manner similar to the control of jack 14 by the manually-adjustable electric signal source 33. In this case each double-acting jack 7 has an electro-hydraulic valve 18 and potentiometer 23, and the control assembly 15 is operable to connect the comparator 28 to the potentiometer of any desired double-acting jack 7.

If, when advancing the conveyor 1, it is necessary for two or more double-acting jacks 7 to apply an advancing force to the conveyor 1 at the same time, an equivalent number of comparators 28 may be provided, the control assembly 15 being operable to connect comparators 28 and associated amplified outputs to the respective doubleacting jacks 7.

We claim:

'1. Mining apparatus including a guide means extending along the working face of a mine for guiding a cutting machine along the working face, a series of fluid-pressureoperated jacks each operable to apply an advancing force to the guide means, and adjustable means responsive to the advance of a portion of the guide means to stop the advance of that portion of the guide means, after an adjustable predetermined advance thereof, by rendering the appropriate jack or jacks inoperative.

2. Mining apparatus according to claim 1 wherein the adjustable means is adjusted by the extension of a jack associated with the said portion of the guide means.

3. Mining apparatus according to claim 1 wherein the adjustable means includes means for producing a signal indicative of the amount of advance of the said portion of the guide means, means for producing a signal indicative of the required amount of advance of the guide means, and comparing means arranged to compare the signals and render the appropriate jack or jacks inoperative when the signals are substantially equal.

4. Mining apparatus according to claim 3 wherein the signals are electric signals.

5. Mining apparatus according to claim 1 wherein the said portion of the guide means is an end portion of the guide means located beyond the end of the working face of the mine.

6. Mining apparatus according to claim 1 wherein the guide means is a conveyor and the end portion carries a conveyor drive assembly.

'7. Mining apparatus according to claim 5 wherein the adjustable means is adjusted by the amount of advance of a portion of the guide means opposite the Working face to cause the end portion of the guide means to be advanced by substantially the same amount as the portion of the guide means opposite the working face.

8. Mining apparatus according to claim 1 wherein the adjustable means is manually adjustable to vary the amount of required advance of said portion of the guide means.

References Cited by the Examiner UNITED STATES PATENTS 3,120,105 2/1964 Kibble et al. 6145.2

FOREIGN PATENTS 816,702 7/1959 Great Britain.

SAMUEL F. COLEMAN, Primary Examiner,

Claims

1. MINING APPARATUS INCLUDING A GUIDE MEANS EXTENDING ALONG THE WORKING FACE OF A MINE FOR GUIDING A CUTTING MACHINE ALONG THE WORKING FACE, A SERIES OF FLUID-PRESSUREOPERATED JACKS EACH OPERABLE TO APPLY AN ADVANCING FORCE TO THE GUIDE MEANS, AND ADJUSTABLE MEANS RESPONSIVE TO THE ADVANCE OF A PORTION OF THE GUIDE MEANS TO STOP THE ADVANCE OF THAT PORTION OF THE GUIDE MEANS, AFTER AN ADJUSTABLE PREDETERMINED ADVANCE THEREOF, BY RENDERING THE APPROPRIATE JACK OR JACKS INOPERATIVE.